モルモット臼歯の神経分布に関する研究 : (付)骨様象牙質の形成状態について
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概要
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Changes in histological structures with growth, especially the formation state of osteodentin in the occlusal third of the teeth, and nerve fibers distributed in the teeth and periodontal tissue were investigated with use of lower molar teeth of guinea pigs from birth to five months after birth when they reach maturity. The results were as follows : 1. The molar teeth of guinea pigs immediately after birth are mature teeth in miniature and morphologically present the structures similar to those of mature teeth. 2. In the occlusal third of the molar teeth of guinea pigs, osteodentin enclosing cells and blood vessels was observed and its width increased gradually with growth and development. At three months after birth, three of six cases showed osteodentin occupying a third or more of the width of the dentin. At five months after birth four of five cases showed significant formation of osteodentin occupying more than a half of the dentin width. 3. The formation of osteodentin seems to center around dystrophic calcification resulting from metabolic disturbance in the pulp tissue caused by chronical and continuous stimulation of attrition and by nutritional deficiency due to narrowing of the pulp cavity. 4. In correspondence with the fact that the molar teeth of guinea pigs at birth already have structures similar to those of the mature ones, the distribution pattern of nerve fibers is also similar to that of the mature ones. The nerve fibers merely increased slightly with growth in the number and diameter. 5. Most of the nerve fibers distributed in the pulp and periodontal membrane run monotonously in parallel to the tooth axis and no formation of large bundles or plexus was observed. 6. Most of the nerve fibers entering into the pulp from the dental papilla entrance showed bending or meander. From the narrow of the pulp cavity to inside the narrow canal, nearly sound nerve fibers with fine branches and nerve fibers with various degeneration such as swelling, laceration, or granular decomposition were observed. 7. The nerve fibers distributed in the pulp were a mixture of unmedullated and medullated nerve fibers and seemed to consist mainly of sensory nerves. 8. The nerve fibers distributed in the periodontal membrane also were a mixture of unmedullated and medullated nerve fibers. Many of the nerve fibers in the gingival lamina showed free nerve endings or club-shaped nerved endings. These fibers are mostly related to touch sensation but those related to pain sensation also were thought to exist.
- 九州歯科学会の論文
- 1983-06-25